SOLUTION: I think this is a basic question. But it has been 10 years since I had any algebra and I have to take a placement course for college courses. Here is my problem: "if the total cost

Algebra.Com
Question 1042637: I think this is a basic question. But it has been 10 years since I had any algebra and I have to take a placement course for college courses. Here is my problem: "if the total cost of x apples is b cents, what is a general formula for the cost, in cents, of y apples?"
I believe I know the answer to this problem, but I need help in understanding why this is the answer. I can get to "by/x" , but I don't remember why I am going through these motions. Is there a law or property that is involved in this problem?
Found 2 solutions by josmiceli, ikleyn:
Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
The "rate" the apples are selling at is:
{ b cents ] / [ x apples ], or
cents/apples
----------------------
If you multiply the "rate" by the number of apples
You get the cost of that many apples, so
=
------------------------
[ cent / apples ] x [ apples ] = [ cents ]
so, the dimensions make sense
Answer by ikleyn(52778)   (Show Source): You can put this solution on YOUR website!
.
if the total cost of x apples is b cents, what is a general formula for the cost, in cents, of y apples?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

1.  If "x" apples cost b cents, then one apple costs  cents.

    Agree?

    Now, if one apple costs  cents, then "y" apples cost  cents.

    Did you get it?


2.  Proportions.

    If "z" is the cost of "y" apples, then you have this proportion

     = .

    Each side is the price of one single apple.

    In proportion, a mean term is the product of the two extreme terms divided  by the other mean term. 

    It gives you

    z = .

    Exactly the same as in the first approach.

On proportions, see the lesson
    - Proportions
in this site.

You have also this free of charge online text-book in Algebra-I
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK
in this site.


RELATED QUESTIONS

I am having a difficult time with this question, its been 10 years since needing to do... (answered by solver91311)
No real question, just a comment: I need to complete college algebra to get my B.A.... (answered by fractalier)
It has been over 24 years since I have used algebra. I have 2 days until I take a test... (answered by glabow)
I am undertaking an Algebra 2 class and have not experienced any math since 1983 so any... (answered by Nate)
It has been a long time since I have done any algebra. A friend of mine is taking an... (answered by scott8148)
If I have 4litres of a 90% alcohol solution how many liters of a 70% solution would would (answered by Alan3354)
I have a question I am having problem with. This should be very simple I know. I am... (answered by Fombitz)
I have to take a math placement test and I never had algebra what should I start with and (answered by xcentaur)
{{{3x^2-9x+5<0}}} It has been years since I have had an algebra class. I cannot... (answered by ichudov,jam123)